Drainage panel

ABSTRACT

A drainage panel for arrangement between rafters and battens of a pitched roof to drain a flow of precipitation from the pitched roof. The drainage panel has a plurality of flow deflectors capable of splitting a single flow of precipitation into a plurality as it flows.

FIELD OF THE INVENTION

This invention relates to a drainage panel for a pitched roof, and in particular to a drainage panel for a pitched roof that includes a roof aperture accommodating a roof component such as a rooflight.

BACKGROUND TO THE INVENTION

The primary function of a roof is to protect a lower space below the roof from external elements such as wind, snow and precipitation. A typical pitched roof includes a plurality of parallel load-bearing rafters that slope from a ridge at the top of the roof to an eave at a lowermost edge of the roof, and a plurality of parallel battens disposed on top of, and extending orthogonally with respect to, the rafters. A pitch angle of the roof is defined between the rafters and a horizontal plane that includes the eave.

Roof covering elements constituted by tiles are affixed along the battens in horizontally-extending rows or courses. Each course of tiles underlaps the course of tiles directly above and overlaps the course of tiles directly below, such that the tiles overlap in a ridge-to-eave direction. The tiles of the roof act as a primary drainage system. Precipitation that falls on the roof flows down the tiles towards the eave and into a gutter arranged beneath and parallel to the eave. The gutter then carries the precipitation away from the roof.

The tiles typically incorporate certain design features to prevent precipitation penetrating between the tiles. For example, within a course of tiles, the left-to-right neighbouring tiles may be arranged to interlock with one another to guard against water penetration between neighbouring tiles of a course. Between the courses, upper and lower neighbouring tiles may be provided with weather checks that guard against ingress of upwardly wind-driven rain or snow. For example, the weather checks may be ridges disposed on the undersurface of a tile, that, in a tiled roof, rest on the upper surface of a tile in the course below. The weather checks guard against ingress of precipitation by increasing the tortuosity of the upward path of precipitation. This is particularly important in low-pitched roofs, which term is understood in the art to mean roofs having a pitch between approximately 10° and approximately 15°.

Roofs often include additional roof components that are accommodated on or in, or that extend through, the roof. For example, components such as windows (known in the art as rooflights), vents, GRP dormers, sun pipes, fire escapes or false chimneys may be incorporated into the roof. Such roof components require an aperture in the tiles of the roof, to allow light, air or the roof component to pass through the tiles.

When such components are incorporated into roofs, it is important that measures are taken to guard against precipitation leaking into the space beneath the roof via gaps between the roof component and the surrounding tiles. In particular, precipitation running off the roof component is prone to leak between the roof component and the course of tiles that extends directly below the roof component (referred to hereafter as the lower bordering course).

It is known, therefore, to provide flashing that supplements the primary drainage system of the tiles to resist penetration of precipitation. For example, the aperture may be encircled by a frame that is surrounded by independent flashings that extends from the frame a short distance up, down and across the roof to surround the frame. Above and to the sides of the aperture, the flashing lies above the battens and below the tiles. Beneath the aperture, a lower portion of the flashing extends downwardly and is raised over an uppermost edge of the lower bordering course, such that the flashing is brought onto an upper surface of the tiles of that course. The lower portion of the flashing therefore incorporates a distinct upward step that brings the lower portion from a position below the tiles to a position above the tiles.

In use, the flashing catches precipitation that falls between the aperture and the surrounding tiles. That precipitation flows downwardly from the area surrounding the aperture onto the lower portion of the flashing. As the precipitation flows down the lower portion, it is guided over the step at the uppermost edge of the lower bordering course, and hence is guided onto the upper surface of the tiles of that course. The precipitation then flows down the upper surface of those and subsequent lower tiles in the usual way.

There are significant disadvantages associated with such known flashing systems, which limit their effectiveness in preventing leakage of precipitation, especially in low-pitched roofs.

Firstly, to raise the lower portion of the flashing over the lower bordering course, the lower portion must be brought between the tiles of the lower bordering course, and the overlapping tiles of the course above. In this way, the flashing lifts the upper course of tiles away from the tiles of the lower bordering course, firstly creating an undesirable gap between the courses and secondly disrupting contact between the weather check of the upper tile and the surface of the lower tile. The gap and the disruption to the weather checks allow ingress of upwardly wind-driven rain between the courses, resulting in leakage.

Secondly, at the sides of the aperture the flashing disrupts the tiles of the roof. The flashing covers the battens, so that the tiles cannot be fixed to the battens in the vicinity of the aperture; however, in the interest of preventing leakage, the tiles must lie as close as possible to the aperture. These conflicting requirements mean that tiles must be cut precisely to size so as to be fixed in place around the aperture, and there is little room for error. An improper job in cutting and laying the tiles, for example by a rushed or negligent tiler, frequently leads to problematic leakage around the aperture. Furthermore, if the tiles are profiled (i.e. having an undulating surface) the tiles may need to be cut at different points across the tiles width to the side of the rooflight on the profile, leaving gaps of varying depth beneath the tiles, further hindering fixing and sealing of the tiles.

Such flashings are still more problematic when used in low-pitched roofs. Where the flashing steps upwardly over the uppermost edge of the lower bordering course, a horizontal trough is defined in the flashing. Precipitation and debris can collect in the trough, preventing effective drainage. This problem can be mitigated to some extent by chamfering the surface of the tile at the top edge immediately below the rooflight to reduce the height of the tile profile and reduce the flashing step height over the tile face. However, this process is time consuming and detrimental to the function of the tile because it effectively reduces the protective length of the cover flashing above the tiles, and it does not, in any case, avoid the problem altogether.

The applicant's earlier patent application number GB1221030.8 describes a drainage panel for use in a roof having a roof aperture that accommodates, for example, a rooflight. The drainage panel surrounds the roof aperture, and is disposed between the rafters and the battens of the roof. Below the roof aperture, the drainage panel extends downwardly from the roof aperture to the eave of the roof, where it overhangs the gutter. In this way, precipitation that runs off the rooflight, or that falls between the rooflight and surrounding tiles, is caught by the drainage panel and directed down the drainage panel to the eave of the roof, where it runs into the gutter.

The drainage panel described in patent application number GB1221030.8 is an effective means of avoiding leakage around a roof aperture. However, the inventors have found that during heavier rainfall, the precipitation falling onto the drainage panel from above the rooflight tends to flow around rooflight to the left or right side of the panel. At each of the left and right sides, the precipitation tends to form a single stream that flows down the respective side of the panel at high and increasing speed and overshoots the gutter at the eaves of the roof, resulting in precipitation running down the walls of the building, or over spilling the gutter onto the ground below which is also undesirable.

Furthermore, although the drainage panel described in GB1221030.8 causes less disruption to the tiles surrounding the roof light than the flashing systems described above, the drainage panel raises the battens of the roof away from the rafters by a small distance, which can cause low-level disruption to the roof tiles. It would be desirable to avoid or reduce such disruption.

Against this background, it is an object of the invention to overcome or mitigate one or more of the problems described above.

STATEMENTS OF THE INVENTION

The invention resides in a drainage panel for arrangement between rafters and battens of a pitched roof to drain a flow of precipitation from the pitched roof, the drainage panel having a plurality of flow deflectors capable of splitting a single flow of precipitation into a plurality of flows.

In this way, the invention provides a drainage panel that, in use, drains a flow of precipitation from the pitched roof, and spits the flow of precipitation into a plurality of flows by means of the deflectors. Each of the plurality of flows is of a smaller volume than single flow that would drain down the drainage panel in the absence of the deflectors. Thus the plurality of flows have a lower momentum than the single flow, and therefore run down the drainage panel at a lower speed. In this way, the plurality of flows emerge from the drainage panel at a relatively low speed and do not overshoot the gutter, but instead flow directly into the gutter without spillage, to be safely carried away from the roof. The risk of water draining down the walls of the building as a result of overshooting the gutter is therefore negligible, and thus water damage to the building is substantially avoided.

The drainage panel may include an aperture for accommodating a roof component, such as a rooflight, so that the drainage panel may be incorporated into a roof to drain precipitation away from the roof component accommodated in the aperture.

In this case, one or more flow deflectors may be arranged below the aperture. Arranging one or more flow deflectors below the aperture is particularly advantageous, as it allows a flow of precipitation below the aperture to be split into a plurality of flows in preparation for the gutter below.

For ease of manufacture, one or more of the flow deflectors may be ridges that project from an upper surface of the drainage panel.

The drainage panel may have one or more flow-splitting arrangements constituted by a group of flow deflectors.

The or each flow-splitting arrangement may include a first deflector that is configured to deflect an incoming flow of precipitation inwardly. The first deflector may project from a longitudinal ridge that extends generally in a ridge-to-eave direction.

The first deflector may lie at an obtuse angle to the longitudinal ridge, such that a flow of precipitation is guided downwardly and inwardly by the first deflector.

A junction between the first deflector and the longitudinal ridge may be curved, to guide a flow of precipitation gently onto the first deflector so as to guard against the flow of precipitation skipping over the first deflector.

The drainage panel may comprise a side deflector that protrudes from the longitudinal ridge above the first deflector and that is configured to deflect an incoming flow of precipitation inwardly. In this way, the side deflector may guide the incoming flow of precipitation to take a desired path in preparation for the first director below.

The side deflector may have a ridge-facing surface that lies at an obtuse angle to the longitudinal ridge.

The or each flow-splitting arrangement may further include a second deflector that is configured to prevent continued inward flow of the incoming flow of precipitation. The second deflector may be a ridge that lies substantially parallel to the ridge-to-eave direction.

The or each flow-splitting arrangement may further include a third deflector that is configured to split the incoming flow into two outgoing flows. The third deflector may be a ridge that lies generally perpendicular to the ridge-to-eave direction.

The drainage panel may comprise a primary flow-splitting arrangement for dividing an incoming primary flow into two outgoing secondary flows, and at least one secondary flow-splitting arrangement arranged below the primary flow-splitting arrangement in a ridge-to-eave direction for dividing an incoming secondary flow into two outgoing tertiary flows. In this way, the flow of precipitation can be divided up into a plurality of flows multiple times, so that the resulting plurality of flows have an even smaller volume, and hence flow at an even slower speed.

The drainage panel may further comprise at least one flow path divider arranged below the or each flow-splitting arrangement to define a plurality of flow paths that receive outgoing flows from the or each flow-splitting arrangement. In this way, each outgoing flow can be retained in a separate flow path, so that the outgoing flows cannot recombine after they have been split out from the incoming flow.

The or each flow path divider may be a longitudinally-extending ridge. The or each flow path divider may extend longitudinally in non-linear fashion, for example in a zig-zag or sinusoidal fashion, so as to force the flow of precipitation to meander as it flows down the drainage panel, thereby slowing the flow of precipitation further. The non-linear ridges also lend strength to the drainage panel.

The or each longitudinally-extending ridge may be hollow to define a channel in an undersurface of the drainage panel. In this way, any moisture that collects beneath the panel (for example, moisture penetrating upwardly from the space below the roof) can escape by running downwardly between the via the channels 74 on the underside of the or each longitudinally-extending ridge.

The drainage panel may include a sheet made of a flexible material, such that when the drainage panel is incorporated into a pitched roof it is distorted to form channels between the battens and crests over the battens. To increase flexibility of the sheet, the sheet may be thin, for example thinner than 3 mm. By making that sheet out of a flexible plastics material, forces exerted on the drainage panel by rafters and battens of the roof can be accommodated by deflection of the drainage panel, rather than by deflection of the battens. Thus, disruption to the battens can be reduced, which in turn reduces disruption to the tiles in the finished roof.

In such embodiments, one or more deflectors may be configured to deflect a flow of precipitation out of a channel and towards a crest, such that the precipitation is deflected uphill. In this way, the deflectors can be configured to counteract a tendency of a flow of precipitation to flow down the drainage panel in the channels.

The drainage panel may have one or more batten spacers on its upper surface for spacing battens above the upper surface of the drainage panel. The batten spacers help to ensure that there is sufficient space between the drainage panel and the battens for precipitation, and any debris washed down the panel by the precipitation, to flow down the panel beneath the battens.

The drainage panel may comprise a sheet having suspension ridges configured to sit over rafters of a roof and channels disposed between the suspension ridges. In this way, the sheet can dip down between the battens to form the channels, and the channels extend between the rafters, below the level of the battens, so that disruption to the battens is minimised still further.

The channels may be of generally rectangular cross section perpendicular to a ridge-to-eave direction, so that the sides of the channels can sit flush against the neighbouring rafters. Each channel may have deflectors that are configured to split a single flow of precipitation in the channel into a plurality of flows.

An upper surface of the drainage panel may be textured so as to reduce the surface tension of liquid running down the drainage panel. Reducing the surface tension of liquid running down the drainage panel in this way slows the flow of liquid, and also helps to prevent the flow of liquid following the trail of a previous flow as it runs down the drainage panel.

The drainage panel may have a plurality of panel sections. For example, the drainage panel may have upper and lower panel sections that are separate pieces. Alternatively, the drainage panel may be formed from a single piece.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention might be more readily understood, reference will now be made, by way of example only, to the following drawings, in which:

FIG. 1 is a perspective view of a tiled pitched roof incorporating a drainage panel according to an embodiment of the invention;

FIG. 2 is a perspective view of the roof of FIG. 1 with its tiles removed;

FIG. 3 is a perspective view of the drainage panel of FIGS. 1 and 2, viewed in an eave-to-ridge direction;

FIG. 4 is a perspective view of the drainage panel of FIG. 3, viewed in an eave-to-ridge direction, and incorporated into a roof such that battens extend across the drainage panel;

FIG. 5 is a partial cross-sectional view of the roof of FIG. 1 incorporating a drainage panel, taken along the line A-A of FIG. 2;

FIG. 6 is a partial detailed view of the drainage panel of FIG. 3, viewed in an eave-to-ridge direction, showing the arrangement of deflectors on the drainage panel below the aperture area;

FIG. 7 is a partial detailed view of an upper portion of the drainage panel of FIG. 3, viewed in an eave-to-ridge direction, showing the path of precipitation falling on the drainage panel above the rooflight.

FIG. 8 is a partial detailed view of a left flow region forming a part of the drainage panel of FIG. 4, showing the paths taken by the flows of precipitation when the drainage panel is in use during heavy rainfall;

FIG. 9 is a perspective view of an upper panel section forming part of the drainage panel of FIG. 3, viewed in an eave-to-ridge direction;

FIG. 10 is a perspective view of a lower panel section forming part of the drainage panel of FIG. 3 viewed in an eave-to-ridge direction;

FIG. 11 is a cross-sectional view of the drainage panel of FIG. 3 along the line B-B;

FIG. 12 is a cross-sectional view of a roof incorporating a drainage panel according to another embodiment of the invention; and

FIG. 13 is a cross-sectional view of a flashing in use in sealing between a rooflight and the drainage panel of FIG. 3.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 illustrates a pitched roof 10 having a plurality of tiles 12 exemplifying roof covering elements, which may alternatively be, for example, slates. The tiles 12 extend from an upper edge 14 of the roof, described here as a ridge, but which may alternatively be a top abutment, to an eave 16 at a lower edge of the roof 10.

A roof aperture 18 is provided in the roof 10, so as to define an opening extending through the roof 10. The roof aperture 18 is surrounded by a frame (not shown), and accommodates a roof component (not shown), which, in the embodiments described below, is exemplified as a rooflight.

FIG. 2 illustrates the structure of the roof 10 that lies beneath the tiles 12. It will be apparent that the roof 10 also includes a plurality of parallel rafters 20 that extend down the roof 10 to the eave 16, and a plurality of parallel tile battens 22 extending above and orthogonally with respect to the rafters 20. A roof underlay such as a breather membrane (not shown) extends across the roof 10 and is provided between the rafters 20 and the battens 22. A fascia board 24 extends along the eave 16.

A drainage panel 26 is laid over the top of the draped underlay and disposed between the rafters 20 and the battens 22. The drainage panel 26 encircles the roof aperture 18, and from the roof aperture 18 down to the eave 16.

The rooflight is supported and held in alignment with the roof aperture 18 by the rafters 20 that neighbour the roof aperture 18. The rooflight is attached to the rafters 20 by suitable fixings, such as brackets, which also serve to transfer the load of the rooflight to the rafters 20.

The drainage panel 26 extends outwardly from the roof aperture 18 up, down and across the roof 10 to surround the roof aperture 18. In all directions, the drainage panel 26 is disposed between the rafters 20 and the battens 22, such that the drainage panel 26 extends under the roof tiles 12. Said another way, an upper face 28 of the drainage panel 26 faces the battens 22 and a lower face of the drainage panel (not shown), faces the rafters 20. Below and to the sides of the aperture 18, the drainage panel 26 is disposed above the underlay. Above the aperture 18, a portion of the underlay overlaps the drainage panel 26.

Above and to the sides of the roof aperture 18, the drainage panel 26 extends a short distance away from the aperture 18. Below the roof aperture 18, the drainage panel 26 extends continuously from the roof aperture 18 to the eave 16.

The drainage panel 26 is supported in the roof 10 by supplementary rafters 32, which are disposed at, and aligned with, respective side edges 34 of the drainage panel 26. Inner sides 33 of the supplementary rafters 32 are spaced apart by a distance that is slightly less than the width of the drainage panel 26. In this way, the side edges 34 of the drainage panel 26 can be supported by, and fixed to, respective supplementary rafters 32. The spacing between outer sides 35 of the supplementary rafters 32 is greater than the width of the drainage panel 26, such that part of an upper surface 36 of the rafters 20 remains uncovered by the drainage panel 26, for attachment of the battens 22.

At the eave 16, a lower end portion 38 of the drainage panel 26 extends a short distance beyond the fascia board 24 and may be disposed above or below the upper edge 40 of the fascia board 24. If the drainage panel 26 is disposed below the upper edge 40 of the fascia board 24, the upper edge 40 is provided with a recess 42 aligned with the drainage panel 26 which allows the fascia board 24 to receive the lower end portion 38. A gutter (not shown) is provided beneath the lower end portion 38 to receive precipitation from the tiles 12 and the drainage panel 26.

Referring now to FIG. 3, which shows the drainage panel 26 in isolation for convenience, in the embodiment illustrated, the drainage panel 26 is formed from upper and lower panel sections 26 a, 26 b. The drainage panel 26 includes a base in the form of a substantially flat, rectangular sheet 49. The sheet 49 is flexible, but of self-supporting stiffness, such that it maintains its substantially flat configuration without external support. The upper face 28 of the sheet 49 is textured. The texture of the upper face breaks the surface tension of any liquid running down the drainage panel 26, thereby reducing the speed at which the liquid flows, and reducing the tendency for flows of precipitation to follow the trail of previous flows.

A rectangular panel aperture 50 is provided in the sheet 49. The panel aperture 50 is offset in the ridge-to-eave direction, such that the panel aperture 50 is closer to an upper end 52 of the drainage panel 26 than a lower end 38 of the drainage panel 26. As shown in FIG. 2, the panel aperture 50 is aligned with the roof aperture 18, and is dimensioned to accommodate the rectangular rooflight and the frame that surrounds it. Thus, the panel aperture 50 is of slightly larger dimensions than the frame surrounding the rooflight. Although the panel aperture 50 is disposed in ‘portrait’ manner it could also be disposed in ‘landscape’ manner. Alternatively the panel aperture 50 could be any convenient shape other than rectangular.

A rectangular frame 54 also surrounds the panel aperture 50. The frame 54 includes four projecting walls that extend orthogonally and continuously away from the upper face 28 of the drainage panel 26. In the assembled roof structure 10, the frame 54 of the drainage panel 26 surrounds and is sealed to the frame surrounding the rooflight by means of a suitable cover flashing, an example of which will be explained in detail later. In this way, the drainage panel 26 sits around, and is held in place, between the rafters 20 and the battens 22 without the need for fixings that would otherwise perforate the drainage panel 26, which could leave the drainage panel 26 prone to leakage, especially if the perforations are inappropriately placed. Alternatively, the drainage panel 26 can hang from the frame surrounding the rooflight.

At the sides of the drainage panel 26, parallel ridges 46 project from the upper face 28 of the drainage panel 26. A central ridge 46 a, parallel to the side ridges 46, also extends down the centre of the drainage panel 26, below the panel aperture 50. Each ridge 46 is of constant height above the upper face 28 of the panel 26. However, the ridges 46 differ in height. Specifically, the heights of the ridges 46 decrease in the outward direction, such that a ridge 46 closest to the panel aperture 50 is the highest and a ridge 46 closest to an outer edge 34 of the drainage panel 26 is the lowest.

The ridges 46, 46 a perform two functions. Firstly the ridges 46, 46 a act as platforms that space the battens 22 of the roof structure 10 apart from the upper face 28 of the drainage panel 26. Secondly, the ridges 46, 46 a define left and right flow regions 26 c, 26 d of the panel 26, with the left flow region 26 c being defined between the left side ridges 46 and the central ridge 46 a, and the right flow region 26 d being defined between the right side ridges 46 and the central ridge 46 a. As precipitation flows down the panel 26 its flow path is restricted by the ridges 46, 46 a to either the left flow region 26 c or the right flow region 26 d.

Below the panel aperture 50, deflectors, generally indicated at 60, and batten spacers, generally indicated at 70, project from the upper face 28 of the drainage panel 26. The deflectors 60 and batten spacers 70 have identical arrangements in the left flow region 26 c and the right flow region 26 d.

The deflectors 60 and batten spacers 70 take the form of narrow ridges that project orthogonally from the upper surface 28 of the drainage panel 26. The deflectors 60 are generally of the same height as the central ridge 46, and the tallest of the side ridges 44 of the drainage panel 26, which in the embodiment illustrated is approximately 10 mm. The batten spacers 70 are generally of a height that is less that the height of the deflectors 60, which in this example is approximately 5 mm.

When the drainage panel 26 is installed in a roof 10, the batten spacers 70 act as platforms that space the battens 22 away from the upper surface 28 of the drainage panel 26, ensuring that there is space between the drainage panel 26 and the battens 22 for flowing precipitation.

When precipitation runs down the panel 26, the deflectors 60 direct the flow of precipitation down the drainage panel 26.

In particular, and according to the invention, the deflectors 60 are configured and arranged to split a single flow of precipitation into a plurality of flows, as will be explained in more detail later.

Better to understand the configuration and arrangement of the deflectors 60 of the drainage panel 26 it is necessary to understand that when the panel 26 is incorporated into a roof 10, the panel is distorted by the rafters 20 and the battens 22, as will now be explained.

The sheet 49 of the drainage panel 26 is made of a flexible plastics material, to permit resilient deformation of the sheet 49. The resilient deformation is also aided by the sheet being thin. In this example, the drainage panel 26 is made of acrylonitrile butadiene styrene (ABS) and is approximately 2 mm thick, although the drainage panel 26 may be made of any suitable material and may be of any suitable thickness consistent with producing the requisite degree of flexibility.

FIG. 4 illustrates the position of the battens 22 across the drainage panel 26 when the drainage panel 26 is incorporated into the roof 10 between the rafters 20 and the battens 22. The battens 22 push on the parallel ridges 46, 46 a at the sides and the center of the panel 26 to exert a downward force that is generally perpendicular to the plane of the sheet 49. This is counteracted by the rafters 20, which exert an opposed upward force on the sheet 49. Because the drainage panel 26 is flexible, the drainage panel is distorted by these opposed forces.

FIG. 5 illustrates the deformation of the sheet 49 when it is incorporated between the rafters 20, 32 and battens 22 of the roof 10. In the region of the ridges 46, 46 a, the downward force exerted by the battens 22 pushes portions of the drainage panel downwardly, out of the plane of the sheet 49 and into the roof. The gradually increasing heights of the ridges 46 moving inwardly means that the panel is pushed progressively further into the roof as the battens 22 extend across the drainage panel 26.

This downward deformation in the vicinity of the ridges 46, 46 a forms channels 44 that run longitudinally in the ridge-to-eave direction. A central channel 44 a is formed in the vicinity of the central ridge 46 a, and left and right side channels 44 b are formed in the vicinity of the side ridges 46.

Between the channels 44, the rafters 20, 32 support the drainage panel 26 above the position of the channels 44 to form corresponding crests 43 that also run longitudinally in the ridge-to-eave direction. In this way, the drainage panel 26 is distorted into a corrugated configuration, with alternating longitudinal crests 43 and channels 44.

The flexibility of the sheet 49 of the drainage panel 26 means that the forces exerted by the battens 22 and the rafters 20 on the drainage panel 26 are accommodated primarily by deformation of the sheet 49, rather than by deflection of the battens 22. This is particularly advantageous, as it means that the battens 22 may extend over the drainage panel 26 substantially without deformation. This allows the tiles 12 to be fixed to the battens 22 with virtually no disruption to the tile arrangement, and in particular without disruption to any interlocks between neighbouring tiles 12.

However, the deformation of the sheet 49 means that when the drainage panel is in use in draining precipitation, the precipitation tends to run towards the lowest points 45 of the channels 44 that are formed by the deformation of the sheet 49, such that the channels 44 form easy flow paths for precipitation running off the panel 26. In the absence of the flow deflectors 60, precipitation running off the drainage panel 26 would therefore down each of the channels 44 in a single flow of large volume. The large volume of water in the single flow results in a large momentum, and hence the single stream would flow at high speed, causing the flow to overshoot the guttering at the eave 14 of the roof 10.

The deflectors 60 are therefore configured to counteract the tendency of the precipitation to run into the channels 44 in single streams. Specifically, the deflectors 60 are configured and arranged to be capable of splitting a single flow of precipitation in each of the left and right flow regions 26 c, 26 d into a plurality of smaller flows. The deflectors 60 are also arranged to guide the flows away from the channels 44 where required, and in particular to guide the flows towards the crests 43 of the left and right flow regions 26 c, 26 d. This means that the deflectors 60 must be configured to guide the flow of precipitation uphill, out of a channel 44 and towards a crest 43.

The configuration and arrangement of the deflectors 60 in the left flow region 26 c will now be described in detail, starting from the panel aperture 50 and moving in the ridge-to-eave direction (i.e. in the order in which the deflectors 60 would be encountered by precipitation flowing down the drainage panel 26), and with reference to FIGS. 6 to 8, which illustrate the deflector arrangement. On FIGS. 6 and 8 the positions of the base 45 of the longitudinal channels 44 is indicated for reference by dashed lines. It should be appreciated that the right flow region 26 d, including the arrangement of the deflectors 60, is a mirror image of the left flow region 26 c, and hence will not be described in detail for conciseness.

Referring to FIG. 6, to the left of the panel aperture 50, a side deflector 62 projects inwardly from the inner most ridge 46. In the embodiment illustrated the side deflector 62 projects into the left flow region 26 c by approximately 10 mm. The side deflector 62 is shaped generally as a trapezium. A ridge-facing surface of the side deflector 62 is angled downwardly (i.e. at an obtuse angle to the longitudinal side ridge 44), so as to guide precipitation inwardly towards a centre of the left flow region 26 c. An eave-facing surface of the side deflector is substantially parallel to the battens 22 of the roof 10, and an inner side surface that joins the ridge-facing and eave-facing surfaces is orthogonal to the eave-facing surface.

Below the panel aperture 50 is a group of deflectors 60 (FIG. 10) that constitute a primary flow-splitting arrangement 63 a. The primary flow-splitting arrangement 63 a includes a first, angled deflector 64, a second, vertical deflector 66 and a third, horizontal deflector 68. The angled deflector 64 extends inwardly and downwardly from the innermost ridge 46, such that the angled deflector 64 extends across the left channel 44 b and towards the crest 43 at a centre of the left flow region 26 c. At the junction between the angled deflector 64 and the side ridge 46 the ridge-face surface is curved, with a shallow radius of curvature. The angled deflector 64 leads towards the vertical deflector 66. The vertical deflector 66 is arranged inwardly of the crest 43, and extends downwardly in the ridge-to-eave direction. Below the vertical deflector 66 is a horizontal deflector 68 that extends horizontally from the left channel 44 b, over the crest 43 and towards the central channel 44 a.

Moving downwardly from the primary flow-splitting arrangement 63 a, two vertical batten spacers 70 extend downwardly from the horizontal deflector 68. Beneath the batten spacers 70 and to the left hand side of the left flow region 26 c, a further side deflector 62 projects inwardly from the inner most ridge. This further side deflector 62 is of substantially the same formation as the side deflector 62 described above. Below the further side deflectors 62 are further batten spacers 70, consisting of a horizontal batten spacer and two vertical batten spacers.

Continuing downwardly, beneath the further batten spacers 70 are two secondary flow-splitting arrangements 63 b, 63 c. Each of the secondary flow-splitting arrangements 63 b, 63 c mimics the primary flow-splitting arrangement 63 a, and in the same manner includes an angled deflector 64 b, 64 c that extends inwardly towards a vertical deflector 66 b, 66 c, and a horizontal deflector 68 b, 68 c disposed below the vertical deflector 66 b, 66 c.

A left secondary flow-splitting arrangement 63 b is disposed at the left hand side of the left flow region 26 c. The angled deflector 64 b of the left secondary flow-splitting arrangement 63 b extends from the innermost ridge 46 of the parallel side ridges 46 towards the crest 43. Conversely, a right secondary flow-splitting arrangement 63 c is disposed at the right hand side of the left flow region 26 c, and the angled deflector 64 c of the right secondary flow-splitting arrangement 63 c extends inwardly from the central ridge 46 a towards the crest 43.

Below the secondary flow-splitting arrangements 63 b, 63 c are three elongate ridges 47 (FIG. 3) that extend downwardly to the end 38 of the panel 26 in a zig-zag fashion. The three elongate ridges 47 divide the left flow region 26 c into four flow paths 48 that lie between the side ridges 46 and the central ridge 46 a that extend to the end 38 of the panel 26. In this way, the elongate ridges 47 constitute flow path dividers.

Referring back to FIG. 1 of the drawings, when the drainage panel 26 is incorporated into a roof 10, and the roof 10 is subjected to heavy rainfall, rain is directed down the roof from the ridge 16 towards the eave 16. When draining precipitation reaches the rooflight, it will flow off the tiles 12 that lie directly above the rooflight and will fall between the tiles 12 and the rooflight, where it will be caught by the drainage panel 26.

Referring now to FIG. 7, precipitation that is caught by the drainage panel 26 above the rooflight will flow down either the left side or the right side of the drainage panel, such that it is directed either to the left flow region 26 c or the right flow region 26 d. In this way, the draining precipitation forms two primary flows 80: one that flows towards the left flow region 26 c and another that flows towards the right flow region 26 d.

The flow of precipitation in the left flow region 26 c will now be described with reference to FIG. 8. It will be appreciated that the flow of precipitation in the right flow region 26 d is a mirror image of the flow in the left flow region 26 c, and so will not be described in detail for conciseness.

As the primary flow 80 enters the left flow region 26 c, the side deflector 62 deflects the flow inwardly away from the side ridge 46 in preparation for the primary flow-splitting arrangement 63 a below. As the primary flow 80 continues down the drainage panel 26, the primary flow 80 begins to flow downhill and back towards the left hand channel 44 a. However, before the primary flow 80 can reach the lowest point 45 of the channel 44 a, the primary flow 80 encounters the primary flow-splitting arrangement 63 a.

The primary flow-splitting arrangement 63 a splits the primary flow 80 into first and second secondary flows 81 a, 81 b. The primary flow 80 is firstly deflected inwardly by the angled deflector 64. The shallow radius of curvature of the angled deflector 64 means that the primary flow 80 hits the angled deflector 64 at a shallow angle. This shallow angle guards against the primary flow 80 skipping over the angled deflector, which would allow the primary flow 80 to avoid the primary flow-splitting arrangement 63.

The angled deflector 64 deflects the primary flow 80 inwardly and out of the left hand channel 44 b. In this way, the angled deflector 64 directs the primary flow 80 uphill, towards the crest 43 of the left flow region 26 c. The primary flow 80 is prevented from flowing into the central channel 44 a by the vertical deflector 66, which forces the primary flow 80 downwardly to the horizontal deflector 68. The first vertical deflector 66 is arranged to direct the primary flow 80 such that the primary flow 80 hits the first horizontal deflector 68 substantially at the crest 43. In this way, when the primary flow 80 hits the horizontal director 68 a first portion of the primary flow 80 runs to the left, towards the left channel 44 b, forming a first secondary flow 81 a, and a second portion of the primary flow 80 runs to the right, towards the central channel 44 a, forming a second secondary flow 81 b, thereby splitting the primary flow 80 into two secondary flows 81 a, 81 b.

Following now the path of the first secondary flow 81 a at the left side of the left flow region 26 c, as the first secondary flow 81 a flows downwardly it tends to flow back towards the left channel 44 b. As it flows back towards the left channel 44 b it encounters the second side deflector 62, which deflects the first secondary flow 81 a back towards the centre of the left flow region 26 c. As the first secondary flow 81 a flows continues to head downwardly from the second side deflector 62, it heads once again towards the left channel 44 b. Once again, before the first secondary flow 81 a reaches the lowest point 45 of the channel 44 b it encounters the secondary flow-splitting arrangement 63 b.

The second flow-splitting arrangement 63 b acts in a manner that is substantially identical to the primary flow-splitting arrangement 63 a to split the first secondary flow 81 a into two tertiary flows 82 a, 82 b. The angled deflector 64 b directs the first secondary flow 81 a inwardly, out of the channel 44 b and towards the vertical deflector 66 b. The vertical deflector 66 b prevents the first secondary flow 81 a continuing to the central channel 44 a and directs it instead towards the horizontal deflector 68 b, where it is split into the two tertiary flows 82 a, 82 b.

Returning now to the second secondary flow 81 b at the right hand side of the left flow region, after the second secondary flow 81 b has been split out from the primary flow 80, it tends to flow towards the central channel 44 a, where it continues downwardly towards the right secondary flow-splitting arrangement 63 c. The right secondary flow-splitting arrangement 63 c splits the second secondary flow 81 b into two further tertiary flows 82 c, 82 d in substantially the same manner as the primary flow-splitting arrangement 63 a and the left secondary flow-splitting arrangement 63 b: the angled deflector 64 c directs the second secondary flow 81 b inwardly, out of the channel 44 b, the vertical deflector 66 c prevents the second secondary flow 81 b continuing to the central channel 44 a and directs it instead towards the horizontal deflector 68 c, where it is split into the two tertiary flows 82 c, 82 d.

Thus, the secondary flow-splitting arrangements 63 b, 63 c split the two secondary flows 81 a, 81 b into four tertiary flows 82 a, 82 b, 82 c, 82 d.

Beneath the secondary flow-splitting arrangements 63 b, 63 c, each of the tertiary flows 82 a, 82 b, 82 c, 82 d is fed into one of the four flow paths 48 defined by the zig-zag ridges 47. The zig-zag ridges 47 retain each tertiary flow 82 a, 82 b, 82 c, 82 d in its own flow path all the way down to the end of the left flow region 26 c and off the end of the drainage panel 26, into the gutter at the eave 14 of the roof 10. The zig-zag nature of the ridges 47, and hence of the flow paths 48 defined between the ridges 47, forces the tertiary flows 82 a, 82 b, 82 c, 82 d to take a meandering path down the panel 26, thereby slowing the progress of the tertiary flows 82 a, 82 b, 82 c, 82 d down the drainage panel 26.

Thus, when a single primary flow 80 enters the left flow region 26 c beneath the panel aperture 50, the deflectors 60 split the primary flow 80 into two secondary flows 81 a, 81 b, and again into four tertiary flows 82 a, 82 b, 82 c, 82 d that exit the drainage panel separately. It will be appreciated the right flow region 26 d mirrors the left flow region 26 c, such that the deflectors 60 in the right flow region 26 d also splits a primary flow into four tertiary flows. In this way, a total of eight tertiary flows are produced by the deflectors 60 of the drainage panel.

Each of the eight tertiary flows 82 a, 82 b, 82 c, 82 d is of a smaller volume than the primary flows 80 that would run down the drainage panel in the absence of the deflectors 60. Thus, it has a lower momentum, and therefore runs down the drainage panel 26 at a lower speed. The speed of the flows down the drainage panel is also slowed by the meandering path that is forced upon the flows by the flow-splitting arrangements, and slowed again by the zig-zag channels 48.

Thus, the effect of the deflectors 60 is that when the eight tertiary flows emerge into the gutter at the eave 14 of the roof 10, they are flowing at a relatively low speed. In this way, the eight tertiary flows do not overshoot the gutter, but instead flow directly into the gutter without spillage, to be safely carried away from the roof 10. The risk of water draining down the walls of the building as a result of overshooting the gutter is therefore negligable, and thus water damage to the building is substantially avoided.

To manufacture the panel 26, each of the upper and lower panel sections 26 a, 26 b is made separately by forming a plastic sheet. The forming of the plastic sheet(s) is conveniently by vacuum forming over a single tool. Alternatively, the or each plastic sheet may be moulded for example, by pressing the plastic sheet between a pair of complementary mould tools.

FIGS. 9 and 10 illustrate the upper and lower panel sections 26 a, 26 b in isolation immediately after being formed. FIG. 10 reveals that the lower panel section 26 a initially includes a deflector-free section 74 below the zig-zag ridges 47. Before the drainage panel 26 is incorporated into a roof, the lower panel section 26 a is cut to fit the roof, for example by cutting the lower panel section along the line C-C, thereby removing the deflector-free section 74, and as much of the remaining panel 26 as is necessary.

The mould tools that are used to press the sheet comprise formations that define the ridges 44, 47, deflectors 60 and batten spacers 70 during pressing. In this way, and as is illustrated in FIG. 10, the longitudinal ridges 44, 47, deflectors 60 and batten spacers 70 are hollow, such that they define corresponding channels 74 on an underside 29 of the panel 26. As is visible in FIG. 11, the channels formed on the underside of the zig-zag ridges 47 extend to the end of the drainage panel 26, and hence open on to the end of the drainage panel 38 above the fascia board 24.

When the panel 26 is in use in the roof 10, any moisture that collects between the roof underlay layer and the lower surface 29 of the panel 26 (for example, moisture penetrating upwardly from the space below the roof through the breathable roof underlay) can escape by running downwardly between the roof underlay layer and the panel 26 via the channels 74 on the underside of the zig-zag ridges 47. In this way, the channels 74 provide an escape path for trapped moisture. Such an escape path would not exist were the underside 29 of the panel 26 to sit flat against the roof underlay across the entire panel 26 or over the upper edge of the fascia board 24 or recess beneath the true fascia board height.

FIG. 12 illustrates in cross-section a drainage panel 126 according to another embodiment. In this embodiment, rather than channels and crests being formed in the sheet 49 by deformation of the drainage panel 26 caused by the forces exerted on the drainage panel 26 by the battens and the rafters, the cross section of the drainage panel 126 perpendicular to the ridge-to-eave direction is shaped such that the panel 126 steps downwardly between the rafters 20, 32 to form rectangular channels 144. In this way, the panel 126 according to this embodiment can be accommodated between the rafters 20, 32 and the battens 22 with no disruption to the battens 22.

Considering the cross section in more detail, and moving inwardly from a left edge of the panel 126, at the left edge of the panel 126, the sheet 149 of the panel 126 sits flush against the supplementary rafter 32 to define a raised portion or a wide ridge 143. The raised portion acts as a suspension ridge 143 from which the panel 126 can be suspended over the rafters 20, 32 when in use.

At an edge of the supplementary rafter 32, the sheet 149 steps downwardly by a distinct step of approximately 10 mm to define a left sidewall 145 a of the channel 144. Continuing inwardly, the sheet 149 extends towards the rafter 20 to define a base 145 of channel 144. At the rafter 20, the sheet 149 steps upwardly to define a right side wall 145 b of the channel 144. The sheet 149 lies flush against the rafter 20 to define a further raised portion 143. The pattern of raised portions 143 across the rafters 20, 32 and the channels 144 between the rafters 20, 32, continues across the sheet 149 to the right side of the panel 126.

When the panel 126 is incorporated into a roof 10, the panel 126 is supported by the rafters 32, 20 at the suspension ridges 143, with the channels 144 hanging below the battens 22. The base 145 of the channel 144 is therefore spaced apart from the battens 22, such that precipitation can flow freely below the battens 22.

Deflectors, not visible in FIG. 12, project from an upper surface 128 of the panel 126. As in the previous embodiment, the deflectors are thin ridges, and are arranged to split a flow of precipitation into a plurality of flows. In the same manner as the embodiment described above, the deflectors are configured and arranged in a flow-splitting arrangement that includes an angled deflector that deflects a flow away from a side wall 127 a, 127 b of the channel 144, a vertical deflector that deflects downwardly, and a horizontal deflector below the vertical deflector that splits the flow into two flows. Flow path dividers, such as the zig-zag ridges described above, are provided below the flow-splitting arrangements to retain the split flows in separate flow paths to the end of the drainage panel 26.

In the embodiment illustrated in FIG. 12, the panel 126 includes a large central channel 144 a and smaller side channels 144 b. In this embodiment, a flow of precipitation is restricted to flow within a single channel 144 and so each flow-splitting arrangement lies within a single channel. For example, deflectors may be arranged in each of the channels 144 a, 144 b to split a single flow in each channel into four flows, thereby resulting in twelve outgoing flows that emerge from the panel.

Thus, in the embodiment of FIG. 12, the flow of precipitation in each channel 144 is split into a plurality of flows by the deflectors. Each of the plurality of flows has a lower volume of water, and hence a lower momentum, such that the plurality of flows move at a lower speed than the speed that would be reached by a combined single flow in the absence of the deflectors. The split flows therefore do not overshoot the gutter, but instead run directly into the gutter to be carried away from the roof.

In both of the embodiments described, the speed at which precipitation runs down the drainage panel is generally sufficient to wash small pieces of debris, such as leaves and twigs, down the drainage panel. However, if the roof is located in an area that is particularly prone to debris, debris may become clogged around the panel aperture.

This can be mitigated by arranging an open-cell foam layer around the frame that surrounds the panel aperture. The open-cell foam allows liquid and small pieces of debris to pass through the foam, whilst catching larger pieces of debris. The larger pieces of debris can then be easily removed from the foam, or the foam can be easily replaced when required.

Because the foam is open-celled, the foam can be easily compressed to accommodate the tiles surrounding the rooflight, so that the arrangement of the tiles around the rooflight is not disrupted by the foam.

As has been mentioned above, in the assembled roof structure 10, the frame 54 of the drainage panel 26 surrounds and is sealed to the frame surrounding the rooflight by means of a suitable cover flashing.

FIG. 13 illustrates a suitable cover flashing 200 in in use in sealing between a frame 56 that surrounds a rooflight (not shown) and a frame 54 that surrounds a panel aperture 50 of a drainage panel 26.

The frame 56 that surrounds the rooflight has an outer face 55 that lies against the frame 54 of the drainage panel 26 when the drainage panel 26 is incorporated into a pitched roof. Above the outer face 55 is a step that extends around the perimeter of the frame. The step includes a ledge 57 that faces upwardly and a riser 58 that extends upwardly, perpendicular to the ledge 57. The riser 58 joins the ledge 57 to an upper surface 59 of the frame 56.

The flashing 200 is a two-part flashing that has lower and upper parts 200 a, 200 b. The flashing 200 may be made of any suitable metal or plastics material, and is typically made out of tin.

The lower part 200 a has includes a lower vertical wall 202 that lies against an outer surface of the frame 54 of the drainage panel 26, a horizontal wall 204 that extends inwardly from the top edge of the lower vertical wall 202 to lie against the ridge 57 of the rooflight frame 56, and an upper vertical wall 206 that extends upwardly from the inner edge of the horizontal wall 204 to lie against the riser 58 of the rooflight frame 56. The upper part 200 b has a substantially ‘L’ shaped cross section, and includes a horizontal wall 208 that lies against the upper surface 59 of the rooflight frame 56, and a short vertical wall 210 that extends downwardly from an outer edge of the horizontal wall 208 to lie against an outer surface of the upper vertical wall 206 of the lower part 200 a of the flashing 200 in a push fit.

To install the flashing, the drainage panel 26 is first placed over the rooflight frame 56. The lower part 200 a of the flashing 200 is fitted over the rooflight frame 56 and the frame 54 of the drainage panel 26. The upper part 200 b is then fitted with a push-fit over the upper surface 59 of the rooflight frame 56 and the upper vertical wall 206 of the lower part 200 a, so as to secure the flashing 200 to the frames 54, 56.

Although in the embodiments described the drainage panel includes a panel aperture for accommodating a rooflight, the panel aperture need not accommodate a roof light but may accommodate other roofing components, and may be of any suitable size or shape.

In other embodiments, the drainage panel need not include a panel aperture at all, but may instead be a continuous sheet.

Although it is advantageous for either the sheet to be made of a flexible material such that channels and crests are formed by deformation of the sheet, or for the sheet to include suspension ridges having channels defined between them such that the channels hang below the battens, this need not necessarily be the case, and the drainage panel may instead be substantially flat and rigid.

The drainage panel need not necessarily be formed from two panel sections. The drainage panel may instead by formed as a single panel section, or may be formed from more than two panel sections. 

1. A drainage panel for arrangement between rafters and battens of a pitched roof to drain a flow of precipitation from the pitched roof, the drainage panel having a plurality of flow deflectors capable of splitting a single flow of precipitation into a plurality of flows.
 2. The drainage panel of claim 1, including an aperture for accommodating a roof component, such as a rooflight.
 3. The drainage panel of claim 2, wherein one or more flow deflectors are arranged below the aperture.
 4. The drainage panel of claim 1, wherein one or more flow deflectors are ridges that project from an upper surface of the drainage panel.
 5. The drainage panel of claim 1, wherein the drainage panel has one or more flow-splitting arrangements constituted by a group of flow deflectors.
 6. The drainage panel of claim 5, wherein the or each flow-splitting arrangement includes a first deflector that is configured to deflect an incoming flow of precipitation inwardly.
 7. The drainage panel of claim 6, wherein the first deflector projects from a longitudinal ridge that extends generally in a ridge-to-eave direction.
 8. The drainage panel of claim 7, wherein the first deflector lies at an obtuse angle to the longitudinal ridge.
 9. The drainage panel of claim 8, wherein a junction between the first deflector and the longitudinal ridge is curved.
 10. The drainage panel of claim 7, wherein the drainage panel comprises a side deflector that protrudes from the longitudinal ridge above the first deflector and that is configured to deflect an incoming flow of precipitation inwardly.
 11. The drainage panel of claim 10, wherein the side deflector has a ridge-facing surface that lies at an obtuse angle to the longitudinal ridge.
 12. The drainage panel of claim 5, wherein the or each flow-splitting arrangement further includes a second deflector that is configured to prevent continued inward flow of the incoming flow of precipitation.
 13. The drainage panel of claim 12, wherein the second deflector is a ridge that lies substantially parallel to the ridge-to-eave direction.
 14. The drainage panel of claim 5, wherein the or each flow-splitting arrangement further includes a third deflector that is configured to split the incoming flow into two outgoing flows.
 15. The drainage panel of claim 14, wherein the third deflector is a ridge that lies generally perpendicular to the ridge-to-eave direction.
 16. The drainage panel of claim 5, wherein the drainage panel comprises a primary flow-splitting arrangement for dividing an incoming primary flow into two outgoing secondary flows, and at least one secondary flow-splitting arrangement arranged below the primary flow-splitting arrangement in a ridge-to-eave direction for dividing an incoming secondary flow into two outgoing tertiary flows.
 17. The drainage panel of claim 5, further comprising at least one flow path divider arranged below the or each flow-splitting arrangement to define a plurality of flow paths that receive outgoing flows from the or each flow-splitting arrangement.
 18. The drainage panel of claim 17, wherein the or each flow path divider is a longitudinally-extending ridge.
 19. (canceled)
 20. (canceled)
 21. The drainage panel of claim 1, wherein the drainage panel comprises a sheet made of a flexible material, such that when the drainage panel is incorporated into a pitched roof it is distorted to form channels between the battens and crests over the battens.
 22. The drainage panel of claim 21, wherein one or more deflectors is configured to deflect a flow of precipitation out of a channel and towards a crest, such that the precipitation is deflected uphill.
 23. The drainage panel of claim 1, wherein the drainage panel has one or more batten spacers on its upper surface for spacing battens above the upper surface of the drainage panel.
 24. (canceled)
 25. (canceled)
 26. (canceled)
 27. (canceled)
 28. The drainage panel of claim 1, wherein the drainage panel has a plurality of panel sections.
 29. (canceled) 